Analysis of Cloud Seeding Experiment by Aircraft: A Case Study of an International Joint Experiment in 2019

In this study, an international joint cloud seeding experiment (International Joint Cloud Observation and Weather Control Experiment 2019, IJCO-WCE 2019) by aircraft was analyzed using numerical simulations, ground observation data, and aircraft observation data. As a result of numerical simulations, it was found that the seeding material was diffused in a direction consistent with the wind direction observed by the aircraft. Further, aircraft observation data showed an increase in average water concentration of clouds and precipitation particles after seeding rather than during seeding. The average water concentration of clouds observed by the Cloud Droplet Probe (CDP) increased by about 59% after seeding than during seeding, and that observed by the Cloud Imaging Probe (CIP) increased by about 82%. In addition, precipitation particles observed by the Precipitation Imaging Probe (PIP) were hardly noticed during seeding, but appeared after seeding.

Winter Storms and Fall-Related Injuries: Is It Safer to Walk than to Drive?

Emergency department visitation data were analyzed using a matched-pair, retrospective cohort method to estimate the effects of winter storms on fall-related injury risks for a midsized urban community in Ontario, Canada. Using a unique definition and classification of winter storm events and dry-weather control periods, relative risks of injury were estimated for total falls and two subcategories (same-level falls involving ice and snow; all other falls) across two storm event types (snowfall only; mixed precipitation). Winter storms were associated with 38% and 102% increases in the mean incidence of same-level falls involving ice and snow during snow events and freezing-rain events, respectively. The incidence of other types of falls was slightly but significantly less during snow events relative to dry-weather control periods. Findings suggest that walking is not safer than driving during winter storms, as same-level falls involving ice and snow accounted for 64% more of the injury burden than motor vehicle collisions. Significant reductions in mean relative risk estimates for fall-related injuries were apparent over the 2009–17 study period indicating possible long-term shifts in exposure, sensitivity, and/or risk-mitigating decisions, actions, and behavior. Consistent and significant effects of government-issued weather warning communications on risk outcomes were not found. Practitioners engaged in developing injury prevention strategies and related public risk messaging, in particular winter weather warnings and advisories, should place additional emphasis on falls and multimodal injury risks in communications related to winter storm hazards.

Chen System as a Controlled Weather Model — Physical Principle, Engineering Design and Real Applications

This paper presents the Chen system as a controlled weather model. Mathematically, the Chen system is dual to the Lorenz system via time reversal. Physically, the Chen system can be viewed as a controlled weather model from the anti-control perspective. This paper illustrates the physical principle of this controlled weather model, and develops an engineering design of the model for real indoor climate (temperature-humidity) regulation, with a perspective on outdoor weather control application.